Nanocomposites are usually polymer composite systems in which nano-sized (typically 1-100 nm) fillers are dispersed in a polymer matrix. The thermal and mechanical behaviors of these systems are typically different from the behaviors of the polymers themselves, or the behaviors of polymer composite systems containing micro-sized or larger fillers. For example, polymers such as polypropylene, polystyrene, and polyester are flammable, and have to be treated with flame retardant material to make them flame resistant.